Pressure loaded tank for hydraulic transmissions



D. `GSSLER Filed Jan. 11 1937 DIETRICH GOSSLER.

Iliff! Ill l 9 Patented June 6, 1939 UNITED sTATEs PATENT OFFICEPRESSURE LOADED TANK FOR HYDRAULIC TRANSMISSIONS Dietrich Gssler,Heidenheim, Germany Application January 11, 1937, Serial No. 119,994

In Germany February 17, 1936 8 Claims. (Cl. 60-54) This inventionrelates to hydraulic transmis-X the transmission, this container beingin the' 15 form of an air-tight tank connected to a pump associated withthe transmission housing in such a manner that the pumpA will vpump theliquid from the housing into the tank until the housing is empty, andtherefore will pump air likewise rinto the tank. This air forms apressure cushion above the liquid, and provides a force urging theliquid into the hydraulic transmission when the operation thereofdemands an additional supply` of liquid.

Another object is to provide a hydraulic transmission with a tank orapliquid container, this tank being constructed to provide a large topsurface for the liquid so as to facilitate the separation of the airfrom the liquid. In the operation o of the hydraulic transmission muchair becomes mixed with the liquid, and this special tank constructionaids in freeing the air from the liquid. Another Vobject is to provideair pressure loaded liquidtank associated with a pump at- 35 vtached toa hydraulic transmission in such a' manner that the single pump, incombination with the air pressure developed in the tank, serves thepurpose of the two pumps hitherto necessary in installations where thetank is placed above or 40 beside the transmission.

In the drawing: i l Figure '1 is a longitudinal vertical section throughthe hydraulic transmission assemblyof l this invention.l

45 Figure 2 is-a`. ltransverse section along the line,

` In general, the hydraulic transmission assembly of this inventionconsists [of one Aor more hydraulic transmission units, such ashydraulic cou- 50 plings or torque converters having' a housing and atank inthe upper partof the housing and conn ected thereto by a pump.This pump is capable of pumping'either oil orar from the housing intothe tank. When the pump has emptied the 55 vhousing and begins to pumpair, this air passes vupwardly through the oil into the space at theItop of the tank, and builds up a pressure cushion of air above the topsurface of the oil. When this pressure reaches a predetermined point,the surplus air discharges through a check valve and a discharge. pipeinto the housing. transmission unit or units require filling, the liquidis forced from the 'tank into the transmission vunit by means of the airpressure at the top of theI tank. In this manner a very rapid filling ofthe transmission is accomplished with the air of but a single pump.

When the Hitherto, it has been customary to place Athe liquid tank forsuch hydraulic transmission beneath the transmissions, if space has beenavailable. 'I'he oillescaping from the hydraulic transmission unitsvtothe housing is collected in this tank and returned to the transmissionunits by means of a pump. If space is lacking for locating the tankbeneath the hydraulic transmission units (hydraulic couplings or torqueconverters) 2 it is necessary to place the tank above or beside thetransmission units. Under these conditions two pumps are necessary. Onepump forces the oil from the transmission housing to the tank and the`other pump illls-` the transmission units with oil from the tank.Hitherto, it has been necessary to employ comparatively large pumps for1 filling the transmission units in order to enable a rapid filling tobe accomplished. It will be understood that the first-mentioned pump isnecessary to pump oil from the housing into the tank in order to preventthe leakage oil from collecting in the sump because otherwise thehydraulic couplings or torque converters would rotate in oil and set upfriction losses as a result.

, Because the oil` in most cases must enter the` .transmission unitsunder pressure, it is not suilicient merelyto place the tank directlyabove the transmission and to allow the oil to be supplied by force ofgravity. The force pumps hitherto used for. filling the transmissionunits, because oi their necessarily large vdimensions in order to keepthe (filling, time at a minimum, have consumed a. large amountof power;This has resultedin a loss in efficiency in the ventire transmission. yIn the present inventionx the single Ypump mentioned fulfills therequirements Iof the two pumps formerly necessary. So long as. oilispresent in the housing the pump pumps-.thisfoil up to the Ytank'. y Thesame pump also pumps whatever air is mixed with the oil. After the oilIhasbeen completely pumped from the housing to the tank, the pump thenpumps airin the same manner.

'Ihis air collects .at the top ofthe tank and cost, weight and spacerequired for the additional pump hitherto necessary. It also enablesthis space to be utilized for-a greater supply of oil,

if this is desired. By upwardly aring the tank it has been made.possible to facilitate the separation of the air from the oil.

Referring to the drawings in detail, Figures 1 and 2 show thetransmission assembly of this in-` vention as consisting of a housing I0 having bearing portions II adapted to support shafts I2 and I3.Connected to the shaft I2 is the casing I4 of the first hydraulic unit,generally designated I5. Connected to the shaft I3 is the secondtransmission unit, generally designated I6. The transmission unit I5 isshown as a hydraulic coupling, and the transmission unit I6 as a torqueconverter. It will be understood, however, that these transmission unitsmay be either hydraulic couplings or torque converters as adapted to theparticular conditions.

The casing I4 is provided with the usual vanes I1, cooperating withsimilar vanes I8 upon a rotorA I9 mounted on the left end of the shaftI3. The casing I4 is `provided with a longitudinal extension 20 alongthe shaft I3, and is connected to the rotor 2I of the torque converterI6. The rotor 2| is provided with vanes 22 which cooperate with fixedguide vanes 23 secured, as at 24, to the tank 25, which in turn, issecured to the housing i III. The torque converter I6 is also providedwith a rotor 26 having vanes 21 cboperating with the varies 22 and 23.The rotor 26 is mounted upon the shaft I3. Liquid is supplied to thehydraulic unit I5 by means of a passageway 28 in the elon'- gatedportion 2li, and a pipe 29 leading therefrom to a valve 30. Similarly,liquid is conducted to the hydraulic unit I6 from the valve 30 by meansof the pipe 3|.

The valve 30 communicates at its upper end, through the passage 32, withthe tank 25 in such a manner as to direct liquid therefrom to thehydraulic units I5 and I6 when such liquid is required by these units.The valve passageway 32 opens into a downwardly extending portion 33 onone side of the tank 25. On the 'other side of the tank is anotherdownwardly extending portion 34 having a passageway 35 forming theoutlet of a pump y36, the inlet 31 of which opens into thel bottompartof the housing I0. The

pump 36 is adapted to pump either oil or air,

according to the particular conditions existing at the time. The top ofthe-tank 25 is closed so as to form an air-tight compartment forcollecting the air which is pumped from` the housing IIJ, through-thqpiimp 36, to the tank 25.

So long asliquid remains in the bottom of the.

at the top of the tank 25, located in the upperl part of the housingAIll.- A port 38 in the upper` y part of the tank 25 opens into apressure relief valve or check valve 39', having a discharge pipe 40leading downwardly to the port 4I in the lower part; of the housingIII.- ,Consequently when the air pumped by the pump .'36 into the upperpart of the tank 25 exceeds the predetermined pressure for which therelief valve- 39 is adjusted, the

latter will open and discharge the excess air through the pipe 40 andport 4I into the lower part of the housing III. In this manner any oilvapor escaping with the excess air is conserved` within the apparatus.While the valve 30 is closed the pump 36 continues to ll the tank 25with oil or air, as the case may be.

'I'he tank 25 is so constructed as to provide a maximum area for the topsurface of the liquid. To this end the bottom walls ofthe tank areflared upwardly, as at 42 and 43, so as to increase the top area of theliquid surface in the tank 25. By this provision the tank is made toaccommodate the space between the hydraulic transmission units I5 and I6and at the same time to provide a large top surface area to facilitatefreeing of the oil from the air.

Any suitable means may be employed for emptying the iiuid powertransmission units I5 and I6, and the details thereof form no part ofthe present invention. In the simplified conventional arrangement shownin Figure 1, at the periphery of unit I5, small leakage ports 45 areprovided, whereas at the periphery of unit I6 a very narrow leakage gap46 is provided. During operation the leakage loss occurring through theports 45 or gap 46 is compensated for by fluid supplied from thepressure-loaded tank 25, through the valve 30 and the pipes 29 and 3|.To empty either or both of the units I5 and I6, the valve 30 is shiftedto cut olf the supply of uid thereto, whereupon the uid remaining in thetransmissionl units exhausts through the ports 45 or gap 46, into thesump formed by the housing II), under the action of centrifugal force.It

will.be understood, however, that\a controllable port arrangement mayalternatively be used, such a's is disclosed in the copendingapplication of Hans F. Canaan, Ser. No. 107,741, led October 26, 1936.

It will be understood that I desire to-comprehend within this inventionsuch modifications as come within the scope of the claims and theinvention.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent, is

1. In a hydraulic transmission, La housing', a hydraulic transmissionunit therein, an air-tight liquid tank, pumping means arranged .to pumpliquid and air from said housing to said tank,

` device adapted to discharge air from said tank from above the liquidlevel thereof, and means for conducting discharged air from saidpressure relief device back to said housing.

2. In a hydraulic transmission, a housing, a hydraulic transmission unittherein, a liquid tank above the lower portion of said housing, pumpingmeans associated with said housing for pumping air andliquid to saidtank, and means utilizing the pressure of the'air inthe top of the tankfor urging liquid from saidl tank into said hydraulic unit, said tankhaving upwardly diverging walls y"adapted to provide an extended areafor the upper portion of the liquid whereby to facilitate the separationof air therefrom-.I

hydraulic transmission unit therein, a partition subdividing saidhousing into a lower liquid tank and a liquidtank above the lowerportion of said housing, an air-liquid pump associated with said 70 y 1,3., In a .hydraulic transmission, a housing, a

oi said tank, and pressure relief means for housing `for pumping air andliquid from said lower tank to said upper tank, and means utilizing thepressure of the air in the top of the tank for urging liquid from saidtank into said hydraulic unit, said partition being xextended downwardly at one portion within said housing, and the outlet from saidpump being directed into said downwardly extended portion.

4. In a hydraulic transmission, a housing, a hydraulic transmission unittherein, a partition subdividing said housing into a lower liquid tankand a liquid tank above the lower portion of said housing, an air-liquidpump associated with .said housing for pumping air and liquid to saidtank, and means 'utilizing the pressure of the air in the top of thetank for urging liquid from said u tank into said hydraulic unit, saidpartition being extended downwardly at one portion within said housingand having an aperture in said downwardly extended portion, andl saidpump being mounted adjacent s aid aperture to pump air and liquid fromsaid lower tank directly into said downwardly extended portion of saidupper tank. 5. In a hydraulicY transmission, a housing, a plurality ofhydraulic transmission units 'on a common shaft therein, a liquid tankarranged between the upper portions of said transmission units withdownwardly extended portions on opposite sides of said shaft, anair-liquid pump adapted to pump liquid and air from said housing to oneof the downwardly extended portions dis.. charging air from said tank.

6. In a hydraulic transmission, a housing, a plurality of hydraulictransmission units therein, a liquid tank associated with the upperportions of said transmission units, pumping means adapted to pumpliquid and airfrom said housing to said tank, means opening into the airspace above the liquid level in said tank and including apressure'relief device for discharging l in, a liquid tank associatedwith the upper por-- tions of said transmission units, and an airliquidpump connected to said tank and adapted to pump liquid and air from saidhousing to said tank, said tank being 'extended' laterally and upwardlyfrom the connection of said pump thereto at the top portion of said tankto provide an increased area for the separation of air from the liquid.

8. In a hydraulic transmission, a housing, a hydraulic transmission unittherein, an air-tight liquid tank having a portion beside saidtransmission unit; and an air-liquid pump arranged to pump air andliquid from the lower portion of said housing to, said tank, said tankbeing extended upwardly and laterally from the inlet of said pump toprovide anincreased area for the separation pf air from the liquid.

DIETRICH GssLER.

